The present application relates to aqueous emulsions containing organosilicon compounds suitable for the impregnation of inorganic materials, and in particular for the impregnation of building materials. In another aspect, the present invention relates to the preparation of the special organosilicon compounds and to the use of the emulsions produced thereby.
Whereas in the past substances used for impregnating brickwork, concrete, etc. frequently contained organic solvents (DE-PS 20 29 446), this is being increasingly avoided in more recent developments. For example, DE-PS 27 51 714 relates to an impregnating agent for porous materials, consisting of an emulsion of alkoxysilanes in water or in water/alcohol mixtures and containing a surfactant as emulsifying agent. These agents, however, frequently have the disadvantage that the addition of surfactant reduces the hydrophobicizing effect of the alkoxysilane. Moreover, these agents have insufficient depth of penetration. The introduction of water-soluble groups into polysiloxanes (so-called "silicone surfactants") according to U.S. Pat. No. 4,661,551 results in microemulsions which can be diluted to any desired degree. However, these must be applied after 12 to 24 hours.
European Patent Applications EP-A 234 024 and EP-A-340 816 describe silane-containing aqueous emulsions which can be prepared with the addition of certain surfactants. Emulsions according to EP-A-340 816 in addition contain a substance which buffers the pH for the purpose of increasing the stability in storage.